1. Field of the Invention
The present invention relates to a process and a device for applying inscriptions on copying papers to surfaces of heat-resistant materials, such as, in particular, mineral objects made of ceramic or glass or those made of metals.
The papers used for this purpose are printed with the aid of Xerox copying devices or using the video print process, said papers being designed as transfer papers and having, on the carrier paper, a plastic coating which can be printed and separated from the paper. Photocopying papers of this type have in printing layer, for example, a binder and a pigment, the so called toner, embedded in said binder. Other papers which may be used are so called video printer papers which, after they have been printed, bear sublimation inks.
2. Description of the Related Art
The use of photocopying papers for applying inscriptions to cups is known. For this purpose, a clamping cuff or heating jaw is placed around the cup under pressure, and presses the paper with the printed side against the cup. The cuff is provided with a heating filament, which heats the layer with the inscription via the carrier paper layer and softens the binder (polyester). After the temperature has been reduced, the paper can be pulled off, the inscription remains on the cup (JP 07242099, DE 4221 295 A1).
The disadvantage with such a procedure is as follows. On the one hand, the heating filament located in the cuff is subjected to an expansion stress which changes during each transfer operation and damages the heating filament; the device is susceptible to faults. On the other hand, the transfer operation is time-consuming, since the heat is built up slowly and the elastic material of the cuff conducts the heat poorly. In order to build up the required temperature (about 200.degree. C.), from 5 to 8 minutes are needed. Inscriptions with an unsatisfactory resistance to washing are produced on the cups, the mechanical loading is disadvantageous for the paper and the quality of the color.